Why Russia still struggles to build capital ships

Would Russia try to build battleships or battlecruisers in this alternate treaty world?

It might try, as it did historically, but weak infrastructure and the loss of admirals and engineers would still prevent a successful programme.

The counterfactual changes treaty construction among the signatories, not the institutional conditions inside Russia. Capital ships demand sustained design, yard, armour, gun, and management capacity. Soviet naval plans repeatedly exceeded what that base could deliver. Political purges further damaged the specialist leadership required to turn ambition into completed ships.